1. Field of the Invention
The present invention relates to a vehicle engine control device, and particularly to a vehicle engine control device in which the safety of additional functions and the performance of escape driving at an emergency are improved in an engine control unit (ECU) for carrying out ignition control of an engine, fuel injection control and the like, especially in a compound type ECU added with, as additional functions, an electronic throttle control function for controlling an opening degree of an intake throttle valve by a driving motor.
2. Description of the Related Art
An engine control unit (hereinafter referred to as an ECU) using a microcomputer is widely used to carry out ignition control and fuel injection control of a vehicle engine. Recently, a compound type ECU added with, as additional functions, an electronic throttle control function for controlling the opening degree of a throttle valve by an electric motor is proposed and is coming into wide use.
This electronic throttle control function is such that the opening degree of an intake throttle valve of an engine is controlled by an electric motor in accordance with the depression degree of an accelerator pedal, and a wireless type one having no accelerator wire is coming into wide use recently.
This type of electronic throttle control device is constructed such that when a power source of the electric motor is switched off at the time of the occurrence of an abnormality, the throttle valve is automatically returned to a position of a predetermined safety throttle valve opening degree by a default mechanism using a return spring.
The safety throttle valve opening degree is set to a valve opening position slightly larger than an idling valve opening position, and in escape driving at the time of the occurrence of an abnormality, an operation of an accelerator pedal becomes ineffective, and one pedal operation is carried out in which vehicle speed is adjusted while the depression degree of a brake pedal is adjusted.
However, if the safety throttle valve opening degree is small, there is a problem that even if the brake is released, a sufficient driving force can not be obtained, and climbing escape driving can not be carried out. On the contrary, if the safety throttle valve opening degree is excessively large, a dangerous state occurs in which even if the brake pedal is sufficiently depressed, it is difficult to stop the vehicle.
Further, it is also necessary to consider such a problem that a default return has not been correctly carried out because of a mechanical abnormality in the throttle valve opening degree control.
As improvement measures to such problems, what is illustrated in FIG. 12(a) or 12(b) is conventionally proposed.
First, the conventional improvement measure illustrated in FIG. 12(a) is an escape driving control in the case where a motor or a throttle valve switching mechanism is abnormal.
An escape driving control circuit shown in FIG. 12(a) includes threshold setting means 1a of an upper limit vehicle speed, vehicle speed detection means 1b, threshold setting means 2a of an idle rotational speed of an engine, rotational speed detection means 2b of the engine, upper limit rotation threshold setting means 2c of the engine, return detection switches 3a and 3a of an accelerator pedal, and judgment switches 3b and 3b of a default return state. Incidentally, reference numeral 4 designates supply fuel control means for controlling a fuel injection amount; and 5, a fuel injection valve.
In FIG. 12(a), in the state where the judgment switches 3b and 3b of the default return state are at normal return positions of illustrated positions, and the return detection switches 3a and 3a of the accelerator pedal are also at illustrated positions of return positions of the accelerator pedal, the fuel injection amount is controlled by the supply fuel control means 4 so that the engine rotational speed comes to have not larger than a threshold set by the idle threshold setting means 2a, and the driving force of the engine is put into a minimum state.
In this state, even if the accelerator pedal is depressed to escape from a site, the fuel injection amount is controlled by the supply fuel control means 4 so that the vehicle speed comes to have not larger than a threshold set by the upper limit threshold setting means 1a. However, even by the driving function using the depression of the accelerator pedal, when the throttle valve opening degree is small, a sufficient vehicle speed can not be obtained, and this driving function using the depression of the accelerator pedal is absolutely a minimum driving function for the purpose of escaping from the site.
At the time of an excessively opened abnormality in which the return opening degree of the throttle valve becomes a default opening degree or more, or when a throttle position sensor is abnormal and the throttle opening degree is unclear, the detection switches 3b and 3b of the default return state are changed over from the illustrated positions, and the supply fuel control means 4 is controlled so that the engine rotational speed comes to have not larger than a threshold set by the upper limit rotational speed setting means 2c. 
What is illustrated in FIG. 12(a) is disclosed in JP-A-2000-97087 (Title of the Invention: THROTTLE VALVE CONTROL DEVICE) (prior art 1), and in the state where the detection switches 3b and 3b of the default return state are at the illustrated positions, the engine rotational speed resulting from the depression of the accelerator pedal is not limited, and the escape driving control illustrated in FIG. 12(a) is suitable for low speed climbing escape driving.
However, in the state where the detection switches 3b and 3b of the default return state are changed over, the control is carried out such that the engine rotational speed comes to have not larger than the threshold set by the upper limit rotation threshold setting means 2c, and in a region of low engine rotational speed, the output torque of the engine is increased in proportion to the rotational speed of the engine, and its proportionality constant is increased or decreased substantially in proportion to the throttle valve opening degree.
Accordingly, in the escape driving control illustrated in FIG. 12(a), even if the upper limit rotational speed of the engine is regulated to the threshold or lower, an actual throttle valve opening degree is uncertain, and it is a problem that the driving torque of the engine is changed by the magnitude of the throttle valve opening degree, and there is a danger that when the throttle valve opening degree is large, braking by the brake pedal becomes difficult.
To this end, if the upper threshold by the upper limit rotation threshold setting means 2c is made low, a sufficient driving force can not be obtained, and especially in the case where the throttle valve opening degree is small, there is a problem that the climbing escape running becomes quite impossible.
FIG. 12(b) illustrates a conventional escape driving control in the case where although a driving motor and a throttle valve opening mechanism are normal, an abnormality exists in another portion. The escape driving control illustrated in FIG. 12(b) includes a throttle valve control part shown in the upper stage of the drawing, and a fuel cut control part shown in the lower stage of the drawing.
The throttle control part of the upper stage of FIG. 12(b) is disclosed in JP-A-HEI2-176141 (Title of the Invention: xe2x80x9cCONTROL DEVICE FOR INTERNAL COMBUSTION ENGINExe2x80x9d) (prior art 2), JP-A-HEI11-141389 (Title of the Invention: xe2x80x9cTHROTTLE CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINExe2x80x9d) (prior art 3), and JP-A-HEI6-229301 (Title of the Invention: xe2x80x9cOUTPUT CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINExe2x80x9d) (prior art 4) in addition to the prior art 1, and is a typical escape driving control in the case where the driving motor and the throttle valve are normal, and the other abnormality exists.
The escape driving control illustrated in FIG. 12(b) includes an accelerator position sensor (hereinafter referred to as an APS) 6a for detecting the depression degree of an accelerator pedal, setting means 7 of an objective throttle valve opening degree responding to the detection output of the APS, a throttle position sensor (hereinafter referred to as a TPS) for detecting a throttle valve opening degree linked with a throttle valve opening and closing control driving motor 9, and PID control means 8 for controlling the motor 9 so that the objective throttle valve opening degree by the setting means 7 coincides with an actual valve opening degree by the throttle position sensor 6b, and this structure is the same as the structure at the time of normal driving.
However, in the case where an abnormality occurs in a portion other than the driving motor 9 or its driving mechanism, the objective throttle valve opening degree by the setting means 7 is made a value suppressed as compared with the normal driving time.
The prior art 2 shows abnormality detection means for a level abnormality, a sudden change abnormality, a relative comparison abnormality and the like in detection output voltages of the accelerator position sensor and the throttle position sensor installed in a double system, and the objective throttle valve opening degree is suppressed at the time of the occurrence of these abnormalities.
The prior art 3 is characterized in that acceleration suppression means 10 is used after the setting means 7, and the control is carried out such that even if the objective throttle valve opening degree is suddenly increased, the actual throttle valve opening degree is gradually increased, and when the objective throttle valve opening degree is decreased, the actual throttle valve opening degree is immediately decreased.
The control of the prior art 3 has a feature that the escape driving is carried out by normal two-pedal driving and there is no feeling of wrongness, however, there is a problem that the objective throttle valve opening degree is suppressed so that the driving torque of the engine is decreased, and sufficient climbing performance can not be obtained.
Particularly, there are problems that a method of specifying a non-defective unit in the abnormality judgment means of the APS or the TPS is not used, and suppression of the objective opening degree is not carried out rationally and quantitatively.
The fuel cut control part of the lower stage of FIG. 12(b) is disclosed in the prior art 4, and not only the objective throttle valve opening degree is suppressed by the setting means 7, but also the fuel cut control is used so that the safety is improved.
This fuel cut control part includes variable threshold setting means 2d for variably setting an upper limit rotational speed of an engine substantially in proportion to the detection output of the accelerator position sensor 6a, and supply fuel control means 4 controls a fuel injection valve 5 so that the actual engine rotational speed comes to have not larger than a threshold set by the variable threshold setting means 2d. However, it is not indicated that what escape driving is carried out in the case where the accelerator position sensor is inferior, and especially in the case where the accelerator pedal is returned, if the detection output voltage of the accelerator position sensor is excessive, there is also a case where a dangerous state occurs in which it is difficult to make a stop by a brake pedal.
On the other hand, JP-A-HEI6-249015 (Title of the Invention: xe2x80x9cCONTROL DEVICE FOR VEHICLExe2x80x9d) (prior art 5) relates to a device including an escape running bypass valve, and an electric motor for controlling an opening degree of a main throttle valve returned to be totally closed by a return spring, and discloses, in the device, escape driving means against an excessively opened abnormality in the case where the main throttle valve is not returned to be totally closed by an abnormality of the driving motor, actuator or the like.
The outline of the prior art 5 is shown in FIGS. 13(a) to 13(d). FIG. 13(a) shows a rest cylinder level map corresponding to the output voltage of a throttle position sensor TPS for detecting a main throttle valve opening degree and the output voltage of an accelerator position sensor APS for detecting a depression degree of an accelerator pedal. The rest cylinder level mentioned here indicates, as shown in FIG. 13(b), a level at which fuel supply to a part of a multi-cylinder engine is stopped and effective cylinders are decreased. In FIG. 13(a), six levels of from level 0 to level 5 are shown, and rest cylinders at the respective levels are shown in FIG. 13(b). FIG. 13(b) shows an example of six cylinders.
Incidentally, FIG. 13(a) shows the rest cylinder levels in the case where a driving range of low speed forward 1, low speed forward 2, forward D, or reverse R is selected as a select position of a transmission, whereas FIG. 13(c) shows the rest cylinder levels in the case where the select position of the transmission is selected in a stop range of parking position P, neutral N or the like.
According to FIG. 13(a), as the depression degree of the accelerator pedal becomes small and the throttle valve opening degree becomes large, the rest cylinder level becomes high, and the number of effective cylinders is decreased. The engine rotational speed corresponding to this is an open loop control in which it is changed by a load state of an engine.
However, as shown in FIG. 13(d), a safety control is added in which when the engine rotational speed exceeds a predetermined upper limit value, fuel cut of all cylinders is carried out.
Incidentally, in FIG. 13(d), the horizontal axis indicates engine cooling water temperature, and the vertical axis indicates engine rotational speed, and a fuel cut region of all cylinders in a driving range is shown in the upper part of the drawing, that is, in the vicinity of an engine rotational speed of 4000 r/min. The fuel cut region of all cylinders in this operation range is a region above a dotted line L1, and the fuel cut of all cylinders has a slight hysteresis characteristic so that it is released when the engine rotational speed is lowered to a dotted line L2. Besides, a fuel cut region of all cylinders in the stop range of the neutral N or the parking P is shown in the lower part of FIG. 13D, that is, in the vicinity of an engine rotational speed of 1700 to 1300 r/min. The fuel cut region of all cylinders in this stop range is a region above a solid line L3, and the fuel cut of all cylinders has a slight hysteresis characteristic so that it is released when the engine rotational speed is lowered to a solid line L4.
The escape driving means according to the prior art 5 as described above is escape driving means in the case where both the accelerator position sensor and the throttle position sensor are normal, and the control of the engine rotational speed is also of the open loop control system, and therefore, there is a problem that for example, an engine rotational speed when the accelerator pedal is returned is much changed by the magnitude of the throttle valve opening degree.
Incidentally, JP-A-HEI6-280656 (Title of the Invention: xe2x80x9cESCAPE RUNNING DEVICE FOR VEHICLExe2x80x9d) (prior art 6) discloses means for carrying out escape driving, instead of the rest cylinder control in the prior art 5, by the increase or decrease of a fuel injection amount and the increase or decrease of an ignition advance to adjust an engine output in the state where the control of the throttle valve can not be carried out.
However, there is a problem that a sufficient engine output adjustment can not be made by only the adjustment of the fuel injection amount and the ignition advance.
Besides, JP-A-2000-320380 (Title of the Invention: xe2x80x9cCONTROL DEVICE FOR INTERNAL COMBUSTION ENGINExe2x80x9d) (prior art 7) discloses an electronic throttle control device provided with a default position return mechanism in which when throttle control becomes impossible, the control of decreasing cylinders is carried out.
For example, it is disclosed that the number of decreased cylinders is made small, medium, or large in accordance with the depression degree (large, medium or small) of an accelerator pedal, that the lower limit value of the number of decreased cylinders is increased in accordance with the increase of the throttle valve opening degree, or that the control of decreasing cylinders is carried out by brake detection means or engine rotational speed detection means.
What is disclosed in the prior art 7 is also the control of decreasing cylinders in the open loop system, and there is a problem that for example, the engine rotational speed when the accelerator pedal is returned is much changed by the magnitude of the throttle valve opening degree.
In addition, JP-A-2001-107786 (Title of the Invention: xe2x80x9cENGINE CONTROL DEVICE AT FAILURExe2x80x9d) (prior art 8) discloses an electronic throttle control device provided with a default position return mechanism, in which with respect to an excessively opened abnormal stop or an excessively closed abnormal stop of a throttle valve, escape running is carried out using, as engine output adjustment means other than a throttle valve control, a fuel injection amount increasing/decreasing control including a fuel cut control and an ignition timing control.
However, there is a problem that a sufficient output adjustment of an engine can not be made only by the adjustment of the fuel injection amount and the ignition advance.
In the above-described prior art, there are problems that the abnormality detection means relating to the added electric throttle control function and the escape driving control corresponding to this are not systematic, and even in the case where the actuator system and the accelerator position sensor are normal, the generated torque of the engine at the time of escape driving is suppressed and climbing performance is lowered, or in the case where the actuator system or the accelerator position sensor is abnormal, braking by a brake pedal becomes difficult, or on the contrary, it becomes impossible to secure a sufficient driving force.
A first object of this invention is to propose a vehicle engine control device which provides various escape driving means for systematically extracting abnormalities of a sensor system, a control system, and an actuator system relating to an electronic throttle control function to cope with an abnormal situation, and includes selection means which does not cause confusion in prompt measures against the occurrence of an abnormality during vehicle traveling.
A second object of this invention is to propose a vehicle engine control device including escape running means which discriminates between single abnormality in which one of a pair of accelerator position sensors and a pair of throttle position sensors becomes abnormal, and both abnormality in which both of them become abnormal, and carries out an accurate and easy operation against this.
A third object of this invention is to propose a vehicle engine control device in which rest cylinder control corresponding to a speed deviation in relation to an objective operation speed is carried out against a severe abnormality in which control of a throttle valve can not be carried out, so that a driving operation of escape running can be eased and safety can be improved.
A vehicle engine control device of this invention includes a transmission in which at least a forward position, a reverse position, a neutral position, and a parking position can be selected by an operation of a selector lever, and is characterized in that
the control device includes a microprocessor, is constructed to receive electric supply from an on-vehicle battery through a power source switch, and includes engine rotational speed detection means for detecting a rotational speed of an engine, fuel injection means for supplying a fuel to the engine, a pair of accelerator position sensors for detecting a depression degree of an accelerator pedal, a pair of throttle position sensors for detecting a throttle valve opening degree of an intake throttle valve of the engine, a driving motor for carrying out an opening and closing control of the intake throttle valve in accordance with outputs of the pair of accelerator position sensors and the pair of throttle position sensors, a motor power source switching element for controlling electric supply to the driving motor, a default position return mechanism for returning the throttle valve opening degree to a default position for escape driving when the motor power source switching element breaks electric supply, and drive control means for the driving motor, and further includes abnormality detection means, an abnormality storage element, lower limit rotation threshold setting means, automatic shift escape running means, and selective shift escape running means,
the abnormality detection means is means for always monitoring operations of a sensor system, a control system, and an actuator system relating to control of the intake throttle valve, detecting whether the intake throttle valve can be controlled, and generating a severe abnormality detection output when the intake throttle valve can not be controlled,
when the abnormality detection means generates the severe abnormality detection output, the abnormality storage element stores this, breaks the motor power source switching element to stop electric supply to the driving motor, and is constructed such that its storage state is reset in at least one of closing and breaking of the power source switch,
the lower limit rotation threshold setting means is means for setting a lower limit rotational speed at which the engine can continue to rotate,
the automatic shift escape running means is means for controlling an engine rotational speed by the fuel injection control means in such a way that when electric supply to the driving motor is stopped, the engine rotational speed detected by the rotational speed detection means of the engine becomes a rotational speed less than a predetermined limiting rotational speed, and becomes a rotational speed greater than a minimum engine rotational speed set by the lower limit rotation threshold setting means, and
the selective shift escape running means is means for controlling the engine rotational speed by the fuel injection control means in such a way that when there is an accelerator position sensor regarded as being normal after electric supply to the driving motor is stopped and the transmission is once selected to be put in the parking position, the engine rotational speed detected by the engine rotational speed detection means becomes a rotational speed less than a variable threshold rotational speed of a value substantially in proportion to the depression degree of the accelerator pedal set by variable threshold rotation setting means, and becomes a rotational speed greater than a minimum engine rotational speed or higher set by the lower limit rotation threshold setting means.
Since the above-described vehicle engine control device of this invention includes the abnormality detection means, the abnormality storage element, the lower limit rotation threshold setting means, the automatic shift escape running means, and the selective shift escape running means, there are effects that for the occurrence of the severe abnormality during vehicle traveling, a danger of applying various escape driving means as a prompt measure is avoided, and escape running by the specific automatic shift escape running means can be carried out, and further, in the case where this severe abnormality is a temporal one by noise or the like, it can be released by restart of the engine, and in the case of a continuous abnormality, more convenient escape running means can be selected by using the selective shift escape means.
Besides, another vehicle engine control device of this invention includes a transmission in which at least a forward position, a reverse position, a neutral position, and a parking position can be selected by an operation of a selector lever, and is characterized in that
the control device includes a microprocessor, is constructed so as to receive electric supply from an on-vehicle battery through a power supply switch, and includes engine rotational speed detection means for detecting a rotational speed of an engine, fuel injection means for supplying a fuel to the engine, a pair of accelerator position sensors for detecting a depression degree of an accelerator pedal, a pair of throttle position sensors for detecting a throttle valve opening degree of the engine, and drive control means for controlling a driving motor which carries out an opening and closing control of an intake throttle valve in accordance with outputs of the pair of accelerator position sensors and the pair of throttle position sensors, and further includes first non-defective sensor detection means, second non-defective sensor detection means, and escape running means,
the first non-defective sensor detection means includes first relative abnormality detection means for generating a relative error output when outputs of the pair of accelerator position sensors are mutually compared and a comparison deviation is excessive, and first individual abnormality detection means for detecting existence of a disconnection and a short circuit for each of the pair of accelerator position sensors and generating an individual error output when an abnormality exists, and is made means for making non-defective unit judgment in such a manner that when both of the pair of accelerator position sensors are not in a state of the disconnection and the short circuit, and a relative abnormality does not occur, both the accelerator position sensors are regarded as being non-defective units, and even if the relative abnormality occurs, when one of the accelerator position sensors is in the state of the disconnection and the short circuit, the other accelerator position sensor is regarded as being a non-defective unit,
the second non-defective sensor detection means includes second relative abnormality detection means for outputting a relative error output when outputs of the pair of throttle position sensors are mutually compared and a comparison deviation is excessive, and second individual abnormality detection means for detecting existence of a disconnection and a short circuit of each of the pair of throttle position sensors and generating an individual error output when an abnormality exists, and is made means for making non-defective unit judgment of the throttle position sensors in such a manner that when both of the pair of throttle position sensors are not in a state of the disconnection and the short circuit, and a relative abnormality does not occur, both the throttle position sensors are regarded as being non-defective units, and even if the relative abnormality occurs, when one of the throttle position sensors is in the state of the disconnection and the short circuit, the other throttle position sensor is regarded as being a non-defective unit, and
the escape running means is means for carrying out escape driving by the drive control means and the fuel injection control means in response to at least one abnormality of a slightest abnormality due to at least one of a single abnormality of the pair of accelerator position sensors and a single abnormality of the pair of throttle position sensors, a slight abnormality due to both abnormality of the pair of throttle position sensors, and a severe abnormality due to both abnormality of the pair of accelerator position sensors.
Since the above-described vehicle engine control device of this invention includes the first non-defective sensor detection means for detecting the non-defective unit of the pair of accelerator position sensors, the second non-defective sensor detection means for detecting the non-defective unit of the pair of throttle position sensors, and the escape running means, there are effects that the abnormality is detected with respect to the pair of accelerator position sensors or the pair of throttle position sensors, and further, when there is a sensor regarded as being a non-defective unit, this is specified and is used in the escape running, and therefore, exact and convenient escape running means can be applied.
Besides, a still another vehicle engine control device of this invention uses a microprocessor, and drives and controls a driving motor for carrying out an opening and closing control of an intake throttle valve of an engine in accordance with an output of a pair of accelerator position sensors for detecting a depression degree of an accelerator pedal and an output of a pair of throttle position sensors for detecting a throttle valve opening degree, the control device includes engine rotational speed detection means for detecting a rotational speed of an engine and fuel injection control means for the engine, and further includes abnormality detection means, escape running means, and rest cylinder control means,
the abnormality detection means is means for always monitoring operations of a sensor system, a control system, and an actuator system relating to control of the throttle valve, discriminating between a severe abnormality in which control of the throttle valve is impossible, and a slight abnormality in which control of the throttle valve is possible, and detecting it,
the escape running means includes at least one of severe abnormality escape running means for controlling the rotational speed of the engine by stopping the control of the throttle valve and by the fuel injection control means, and slight abnormality escape running means for suppressing the rotational speed of the engine by the fuel injection control means while carrying out the control of the throttle valve, and
the rest cylinder control means is speed control means for increasing or decreasing the number of rest cylinders in which fuel injection is stopped, in accordance with a magnitude of a relative speed deviation between an objective engine rotational speed and an engine rotational speed detected by the engine rotational speed detection means, to obtain the engine rotational speed substantially equal to the objective engine rotational speed.
Since the above-described vehicle engine control device of this invention includes the rest cylinder control means in addition to the abnormality detection means and the escape running means, escape running can be carried out by the rest cylinder control means at the time of the occurrence of the abnormality, and further, since this rest cylinder control means increases or decreases the number of rest cylinders in which fuel injection is stopped, in accordance with the deviation speed between the objective engine rotational speed and the actual engine rotational speed, there are effects that fluctuation in the rotational speed of the engine in accordance with the load state of the engine is low, and safe escape running can be carried out.